IIHR Nutrient Trading Update

Transcription

1 IIHR Nutrient Trading Update Larry Weber, Director, IIHR-Hydroscience & Engineering Antonio Arenas Amado, Assistant Research Scientist Chad Drake, PhD Candidate Monday, October 10, 2016

2 The overall goal of this research is to develop the scientific framework for a nutrient trading system in Iowa. Specific objectives: 1. Develop a physically-based hydrologic and water quality watershed model of Catfish Creek to determine the coupled water quantity and quality benefits of agricultural conservation practices 2. Develop riverine and terrestrial (crop) nitrogen process models and couple to the physically-based hydrologic model to simulate nitrogen fate and transport 3. Use numerical simulations to evaluate the performance of individual conservation practices 4. Perform integrated watershed modeling in Catfish Creek to quantify the nitrogen load and flow reductions possible at the watershed scale under different practice scenarios 2

3 The broader motivation for this research stems from the Gulf Hypoxia. June/July 2016: 14,460 km 2 (5,580 mi 2 ) 3

4 Gulf Hypoxia Task Force Goals: Load 2016 data: Oct 2015 May

5 Gulf Hypoxia Task Force Goals: Area 5

6 The Iowa Nutrient Reduction Strategy (INRS) identifies specific nutrient reduction goals and offers nutrient trading as a water quality restoration technique. Table 1 from the INRS (2014) Nitrogen Load Reduction Phosphorus Load Reduction Point Source 4% 16% Non-Point Source 41% 29% Total 45% 45% 6

7 Nutrient trading is a voluntary, conceptual framework to improve water quality. Primary motivation: point source regulation and cost CONSERVATION Farm reduces nutrient levels beyond requirem ents to gain credit Nutrie n t Tradin g: Nutrient reduction at a lower cost $$$ Pollution source pays farmer for credit to m eet regulations 7

8 A physically-based modeling framework is being used to achieve the goals of this study. MIKE SHE Hydrologic Processes Mathematical/Numerical Description DHI

9 Catfish Creek 9

10 The Catfish Creek MIKE SHE hydrologic model was built using publically available datasets and model parameters derived from literature. 10

11 MIKE SHE is coupled to MIKE 11 to simulate river discharges and water levels. Catfish Creek MIKE 11 Network MIKE SHE Mesh and Coupling to MIKE 11 11

12 Catfish Creek MIKE SHE Model Development 100 m cells (18,655 surface nodes) 139 nodes per UZ column 2 SZ layers (50 m vertical extent) 5 MIKE 11 branches 63.2 stream miles Ground Elevation (m) Y Z X : X to Z ratio: 12 12

13 A water balance approach is being used to calibrate the Catfish Creek hydrologic model to Ratio Target Literature/Study Values References Q/P Schilling & Libra Schilling & Wolter Bradley Drake 2016 ET/P McDonald Sanford and Selnick Bradley Drake 2016 E/ET , 0.33 Kang et al T/ET , 0.74 Kang et al ±0.15 Schlesinger & Jasechko Berkelhammer et al Q b /Q , 0.62 Schilling & Libra , 0.67 Schilling & Wolter Bradley StreamStats Drake

14 The simulated annual water balance for Catfish Creek is reasonable. 14

15 Visualization 15

16 Catfish Creek Instrumentation NFCTFSH01 WQ26 WQ25/CTFSHCR01 GRNGRCR01 16

17 Catfish Creek Water Quality WQ25: 41.1 mi 2, 23% agric., 11% developed WQ26: 13.2 mi 2, 15% agric., 52% developed 17

18 Wetland Evaluation 18

19 Slough Creek provides an opportunity to evaluate nitrogen removal processes in a relatively well monitored CREP wetland WQS8 WQS12 19

20 Following the same methodology used for Catfish Creek, a MIKE SHE hydrologic model was developed for Slough Creek that was calibrated to annual water balance ratios. 20

21 Slough Creek MIKE SHE Model Development 30 m cells (18,440 surface nodes) 79 nodes per UZ column 2 SZ layers (10 m vertical extent) 5 MIKE 11 branches 6.5 stream miles 21

22 The simulated annual water balance for Slough Creek is reasonable. 22

23 Visualization 23

24 Water quality simulations in MIKE 11 were performed to assess nitrate removal dynamics in the Slough Creek wetland. MIKE 11 Ecolab Study Domain: WQS12 WQS8 Comparison Point: WQS8 Impose upstream boundary conditions from WQS12 and simulated hydrology MIKE 11 Ecolab Study Domain 24

25 Best Simulated Nitrate Concentration: 2014 Sim. N-Load In (WQS12): 27.3 lb/ac Sim. N-Load Out (WQS8): 15.4 lb/ac Sim. N-Load Out (k den = 0.3d -1 ): 16.4 lb/ac Simulated vs Measured 25

26 Best Simulated Nitrate Concentration: 2015 Sim. N-Load In (WQS12): 13.1 lb/ac Sim. N-Load Out (WQS8): 3.0 lb/ac Sim. N-Load Out (k den = 0.3d -1 ): 6.2 lb/ac Simulated vs Measured 26

27 Future work centers on simulating nitrogen fate and transport for other conservation practices. Chronological Order Future Work Topic Description/Comments Related Objective 1 Improve simulated hydrology at Use radar rainfall, implement snowmelt, expand 1 seasonal and monthly time scales MIKE 11 network, review ET and subsurface characterizations 2 Develop riverine and terrestrial Necessary for evaluating nutrient reduction benefits 2 nitrogen process models in Ecolab of selected practices 3 Select agricultural conservation Wetlands 3 practices to evaluate Proposed: farm ponds, cover crops, bioreactors, saturated buffers 4 Use numerical simulations to Perform a sensitivity analysis to model parameters 3 evaluate each practice 5 Quantify watershed scale benefits of different practice scenarios in Catfish Creek Targeted placement of practices, evaluate variable agricultural management decisions and climate change projections 4 27